The corepressor CtBP2 is required for proper development of the mouse cerebral cortex.

The development of the cerebral cortex depends on numerous parameters, including extracellular cues and microenvironmental factors that also affect gene expression. C-Terminal Binding Proteins (CtBPs) 1 and 2 are transcriptional co-repressors which have been shown to be critically involved in embryonic development. CtBPs are oxygen sensing molecules, and we have previously demonstrated an important role for CtBP1 in integrating oxygen levels and BMP-signaling to influence neural progenitor fate choice. In turn, CtBP2 has been associated with neurodevelopment and neurological disease, and we have shown that CtBP2 acetylation and dimerization, required for proper transcriptional activity, are regulated by microenvironmental oxygen levels. Yet, the putative function of CtBP2 in mammalian cortical development and neurogenesis in vivo is still largely unknown. Here we show that CtBP2 was widely expressed by neural stem and progenitor cells (NSPCs) as well as neurons during cortical development in mice. By using in utero electroporation of siRNA to reduce the levels of CtBP2 mRNA and protein in the developing mouse brain, we found that the NSPC proliferation and migration were largely perturbed, while glial differentiation under these conditions remained unchanged. Our study provides evidence that CtBP2 is required for the maintenance and migration of the NSPCs during mouse cortical development.

Oxygen-dependent acetylation and dimerization of the corepressor CtBP2 in neural stem cells.

The transcriptional corepressor CtBP2 is essential for proper development of the nervous system. The factor exerts its repression by interacting in complexes with chromatin-modifying factors such as histone deacetylases (HDAC) 1/2 and the histone demethylase LSD1/KDM1. Notably, the histone acetyl transferase p300 acetylates CtBP2 and this is an important regulatory event of the activity and subcellular localization of the protein. We recently demonstrated an essential role for CtBPs as sensors of microenvironmental oxygen levels influencing the differentiation potential of neural stem cells (NSCs), but it is not known whether oxygen levels influence the acetylation levels of CtBP factors. Here we show by using proximity ligation assay (PLA) that CtBP2 acetylation levels increased significantly in undifferentiated, proliferating NSCs under hypoxic conditions. CtBP2 interacted with the class III HDAC Sirt1 but this interaction was unaltered in hypoxic conditions, and treatment with the Sirt1 inhibitor Ex527 did not result in any significant change in total CtBP2 acetylation levels. Instead, we revealed a significant decrease in PLA signal representing CtBP2 dimerization in NSCs under hypoxic conditions, negatively correlating with the acetylation levels. Our results suggest that microenvironmental oxygen levels influence the dimerization and acetylation levels, and thereby the activity, of CtBP2 in proliferating NSCs.

Seroprevalence of Toxoplasma, Rubella and Cytomegalovirus in Women of Fertility Age in Our Region

Objective: Toxoplasma gondii (T. gondii), Rubella and Cytomegalovirus (CMV) infections can cause severe morbidity in the fetus when transmissed during pregnancy. In our study, it was aimed to examine the seropositivity rates for T. gondii, Rubella and CMV infections in women of childbearing age who applied to our hospital. Methods: Anti-Toxoplasma IgG, anti-Toxoplasma IgM, anti-Rubella IgG, anti-Rubella IgM, anti-CMV IgG and anti-CMV were studied in women of childbearing age (18-49 years old) who applied to our hospital's outpatient clinics between January 2018 and December 2020. The tests were performed in our microbiology laboratory using the ELISA method on Architect i2000 (Abbott, USA) and COBAS e601 (Roche, Germany) devices. Results: As a result of the data obtained, the percentages of IgM and IgG positivity for anti-Toxoplasma were calculated as 1.4% and 30.9%, respectively. Anti-Rubella IgM positivity was 0.7%, anti-Rubella IgG positivity was 91%, anti-CMV IgG positivity was 98.8%, and anti-CMV IgM positivity was 2%. Conclusion: Having its own seroprevalence for each region has is important in terms of planning pregnancy screenings. The seropositivity rates in our region are in line with other studies in the country. Since CMV seropositivity is very high in the population and there is no effective treatment or vaccine, screening may not be not necessary. T. gondii and Rubella screenings can be recommended due to the lower immunity rates and the availability of vaccine and treatment options.

Impact of Health Workers' Choice of COVID-19 Vaccine Booster on Immunization Levels in Istanbul, Turkey.

BACKGROUND: There are limited data regarding short- and medium-term IgG antibody levels after the CoronaVac and BNT162b2 vaccines. This study aimed to investigate the antibody responses of health workers who initially received two doses of CoronaVac one month apart followed by a booster dose of either CoronaVac or BNT162b2, as well as determine whether either vaccine provided superior results. METHODS: This research represents the second phase of a mixed-methods vaccine cohort study and was conducted between July 2021 and February 2022. The participants (n = 117) were interviewed in person and blood samples were collected before and at 1 and 6 months after the booster vaccination. RESULTS: BNT162b2 was found to have greater immunogenic potential than CoronaVac (p < 0.001). Health workers without chronic disease exhibited statistically significant increases in antibody levels after both vaccines (p < 0.001), whereas only BNT162b2 caused a significant increase in antibody levels in participants with chronic disease (p < 0.001). Samples obtained before and at 1 and 6 months after the booster vaccination revealed no age- or sex-based differences in IgG-inducing potential for either vaccine (p > 0.05). Antibody levels were comparable in both vaccine groups before the booster regardless of COVID-19 history (p > 0.05); however, antibody levels were significantly higher after the BNT162b2 booster at 1 month (<0.001) and at 6 months, except among participants who had a positive history of COVID-19 infection (p < 0.001). CONCLUSIONS: Our results suggest that even a single booster dose of BNT162b2 after initial vaccination with CoronaVac provides a protective advantage against COVID-19, especially for risk groups such as health workers and those with chronic diseases.

RBPJkappa-dependent signaling is essential for long-term maintenance of neural stem cells in the adult hippocampus.

The generation of new neurons from neural stem cells in the adult hippocampal dentate gyrus contributes to learning and mood regulation. To sustain hippocampal neurogenesis throughout life, maintenance of the neural stem cell pool has to be tightly controlled. We found that the Notch/RBPJκ-signaling pathway is highly active in neural stem cells of the adult mouse hippocampus. Conditional inactivation of RBPJκ in neural stem cells in vivo resulted in increased neuronal differentiation of neural stem cells in the adult hippocampus at an early time point and depletion of the Sox2-positive neural stem cell pool and suppression of hippocampal neurogenesis at a later time point. Moreover, RBPJκ-deficient neural stem cells displayed impaired self-renewal in vitro and loss of expression of the transcription factor Sox2. Interestingly, we found that Notch signaling increases Sox2 promoter activity and Sox2 expression in adult neural stem cells. In addition, activated Notch and RBPJκ were highly enriched on the Sox2 promoter in adult hippocampal neural stem cells, thus identifying Sox2 as a direct target of Notch/RBPJκ signaling. Finally, we found that overexpression of Sox2 can rescue the self-renewal defect in RBPJκ-deficient neural stem cells. These results identify RBPJκ-dependent pathways as essential regulators of adult neural stem cell maintenance and suggest that the actions of RBPJκ are, at least in part, mediated by control of Sox2 expression.

SPG4 gene promoter regulation via Elk1 transcription factor.

The most common cause of autosomal dominant hereditary spastic paraplegia, that is characterized with axonal degeneration in corticospinal tracts and posterior columns, is known to be caused by mutations in the SPG4 gene which encodes spastin, a microtubule severing ATPase belonging to AAA family. Spastin promotes the formation of microtubule networks that are essential for axon growth and branching which are important for neuronal plasticity. Mutations observed in SPG4 gene of hereditary spastic paraplegia patients have been shown to cause reduced spastin levels. In addition to mutations, transcriptional regulation of spastin gene expression may also affect spastin level. ETS (E Twenty Six-specific)-domain transcription factor, Elk1, has been shown to be important for synaptic plasticity and interact with microtubules. In this study, we aimed to identify the critical promoter regions of SPG4 gene and effects of Elk on SPG4 gene expression. We identified 700 bp TATA-less promoter including a critical CpG island as an optimal promoter, and deletion of the CpG island gradually decreased the SPG4 promoter activity. In addition, we identified the binding sites of Elk1 on the SPG4 promoter by EMSA. Over-expression of Elk1 showed that it repressed the SPG4 promoter and also decreased spastin protein level in SHSY-5Y cells.

Ligand-independent signaling by disulfide-crosslinked dimers of the p75 neurotrophin receptor.

Dimerization is recognized as a crucial step in the activation of many plasma membrane receptors. However, a growing number of receptors pre-exist as dimers in the absence of ligand, indicating that, although necessary, dimerization is not always sufficient for signaling. The p75 neurotrophin receptor (p75(NTR)) forms disulfide-linked dimers at the cell surface independently of ligand binding through Cys257 in its transmembrane domain. Here, we show that crosslinking of p75(NTR) dimers by cysteine-scanning mutagenesis results in constitutive, ligand-independent activity in several pathways that are normally engaged upon neurotrophin stimulation of native receptors. The activity profiles of different disulfide-crosslinked p75(NTR) mutants were similar but not identical, suggesting that different configurations of p75(NTR) dimers might be endowed with different functions. Interestingly, crosslinked p75(NTR) mutants did not mimic the effects of the myelin inhibitors Nogo or MAG, suggesting the existence of ligand-specific activation mechanisms. Together, these results support a conformational model of p75(NTR) activation by neurotrophins, and reveal a genetic approach to generate gain-of-function receptor variants with distinct functional profiles.

Evaluation of Nigella sativa oil loaded electrospun polyurethane nanofibrous mat as wound dressing.

Electrospun nanofibers have a natural wound healing effect due to their similarity to the extracellular matrix (ECM). Nigella sativa oil, which has therapeutic properties, is used for a wide variety of applications in traditional medicine. The aim of this study was to investigate the release characteristic and wound healing performance of Nigella sativa oil (NSO) loaded polyurethane (PU) electrospun nanofibrous mats in wound dressing applications. In addition, the antibacterial activity and cytotoxicity of the electrospun mats were studied. Analyses using a scanning electron microscope (SEM) showed that PU/NSO nanofibrous mat with an average fiber diameter of 416 ± 66 nm were successfully fabricated. NSO was released at a maximum ratio of 30% from the electrospun mat, and the Korsmeyer-Peppas model was identified as best for determining the release mechanism. Significant antibacterial activity was observed against Staphylococcus aureus (90.26%) and Escherichia coli (95.75%). The developed PU/NSO nanofibrous mat increased the cell viability more than 100% in human umbilical vein endothelial cell line (HUVEC) cell line. The NSO loaded PU nanofibrous mat significantly promoted the wound healing process on a rat wound model, and its wound closure reached approximately 85% compared to the control groups on the 9th day (p < 0.01). The results indicated PU/NSO nanofibrous mat is a suitable candidate for a wound dressing.

Effects of partial and complete replacement of added phosphates with encapsulated phosphates on lipid oxidation inhibition in cooked ground meat during storage.

The objective of this research was to investigate the influence of various levels (0.0, 0.1, 0.2, 0.3, 0.4, 0.5%) of added encapsulated polyphosphates (sodium tripolyphosphate; sodium pyrophosphate) combined with unencapsulated polyphosphate to total 0.5% on the inhibition of lipid oxidation in cooked ground meat (beef, chicken) during refrigerated storage (0, 1, 7 d). The use of sodium tripolyphosphate (encapsulated sodium tripolyphosphate, unencapsulated sodium tripolyphosphate) led to lower cooking loss compared to sodium pyrophosphate in both meat species (p < 0.05). Increasing encapsulated sodium tripolyphosphate up to 0.3% decreased cooking loss in ground beef (p < 0.05). Added encapsulated polyphosphate at 0.5% had the same effect on pH as 0.5% unencapsulated polyphosphate in the cooked ground beef and chicken. A higher accumulation of orthophosphate was determined in the samples with sodium tripolyphosphate compared to those with sodium pyrophosphate (p < 0.05). Inclusion of a minimum of 0.1% encapsulated polyphosphate decreased thiobarbituric acid reactive substances and lipid hydroperoxides on 7 d. Increasing encapsulated sodium tripolyphosphate and encapsulated sodium pyrophosphate up to 0.2% in beef decreased thiobarbituric acid reactive substances at 7 d. Addition of 0.4% encapsulated sodium tripolyphosphate and 0.3% encapsulated sodium pyrophosphate in chicken prevented any increase in TBARS during storage. Incorporating encapsulated sodium pyrophosphate at 0.3% inhibited lipid hydroperoxide formation in beef and chicken. The meat industry could achieve enhanced lipid oxidation inhibition by replacing some of the unencapsulated polyphosphate with encapsulated polyphosphate in their product formulations.

Multicellular Interactions in 3D Engineered Myocardial Tissue.

Cardiovascular disease is a leading cause of death in the US and many countries worldwide. Current cell-based clinical trials to restore cardiomyocyte (CM) health by local delivery of cells have shown only moderate benefit in improving cardiac pumping capacity. CMs have highly organized physiological structure and interact dynamically with non-CM populations, including endothelial cells and fibroblasts. Within engineered myocardial tissue, non-CM populations play an important role in CM survival and function, in part by secreting paracrine factors and cell-cell interactions. In this review, we summarize the progress of engineering myocardial tissue with pre-formed physiological multicellular organization, and present the challenges toward clinical translation.

Mammalian FMRP S499 Is Phosphorylated by CK2 and Promotes Secondary Phosphorylation of FMRP.

The fragile X mental retardation protein (FMRP) is an mRNA-binding regulator of protein translation that associates with 4-6% of brain transcripts and is central to neurodevelopment. Autism risk genes' transcripts are overrepresented among FMRP-binding mRNAs, and FMRP loss-of-function mutations are responsible for fragile X syndrome, the most common cause of monogenetic autism. It is thought that FMRP-dependent translational repression is governed by the phosphorylation of serine residue 499 (S499). However, recent evidence suggests that S499 phosphorylation is not modulated by metabotropic glutamate receptor class I (mGluR-I) or protein phosphatase 2A (PP2A), two molecules shown to regulate FMRP translational repression. Moreover, the mammalian FMRP S499 kinase remains unknown. We found that casein kinase II (CK2) phosphorylates murine FMRP S499. Further, we show that phosphorylation of FMRP S499 permits phosphorylation of additional, nearby residues. Evidence suggests that these nearby residues are modulated by mGluR-I and PP2A pathways. These data support an alternative phosphodynamic model of FMRP that is harmonious with prior studies and serves as a framework for further investigation.

Histological evaluation of wound healing performance of electrospun poly(vinyl alcohol)/sodium alginate as wound dressing in vivo.

Poly(vinyl alcohol)/sodium alginate nanofibrous mats were produced by electrospinning method at optimum process parameters. Evaluation of alginate-based electrospun nanofibrous mats as a wound dressing material and their comparison to commercially available wound dressings produced with conventional methods were carried out in vivo. Tissue specimens were examined histopathologically on 4th, 6th, 15th, 21st postoperative days. In contrast to other dressings it was observed that nanofibrous mat could survive on the wound crust in early stages of healing. In terms of epithelization, epidermis characteristics, vascularization and formation of hair follicles, nanofibrous mat showed the best healing performance. This could be explained with presence of nanofibrous mat acting as an artificial skin on the wound region until new tissue regenerated.

CtBPs sense microenvironmental oxygen levels to regulate neural stem cell state.

Bone morphogenetic proteins (BMPs) secreted by the dorsal neural tube and overlying ectoderm are key signals for the specification of the roof plate and dorsal interneuron populations. However, the signals that confer nonneurogenic character to the roof plate region are largely unknown. We report that the roof plate region shows elevated oxygen levels compared to neurogenic regions of the neural tube. These high oxygen levels are required for the expression of the antineuronal transcription factor Hes1 in the roof plate region. The transcriptional corepressor CtBP is a critical mediator of the oxygen-sensing response. High oxygen promotes a decrease in the CtBP occupancy of the promoter of Hes1. Furthermore, under conditions of high oxygen and BMP, CtBP associates with HES1 and represses neurogenesis. We propose that CtBP integrates signals originating from microenvironmental levels of oxygen and BMP to confer nonneurogenic character to the roof plate region.

Activation of the p75 neurotrophin receptor through conformational rearrangement of disulphide-linked receptor dimers.

Ligand-mediated dimerization has emerged as a universal mechanism of growth factor receptor activation. Neurotrophins interact with dimers of the p75 neurotrophin receptor (p75(NTR)), but the mechanism of receptor activation has remained elusive. Here, we show that p75(NTR) forms disulphide-linked dimers independently of neurotrophin binding through the highly conserved Cys(257) in its transmembrane domain. Mutation of Cys(257) abolished neurotrophin-dependent receptor activity but did not affect downstream signaling by the p75(NTR)/NgR/Lingo-1 complex in response to MAG, indicating the existence of distinct, ligand-specific activation mechanisms for p75(NTR). FRET experiments revealed a close association of p75(NTR) intracellular domains that was transiently disrupted by conformational changes induced upon NGF binding. Although mutation of Cys(257) did not alter the oligomeric state of p75(NTR), the mutant receptor was no longer able to propagate conformational changes to the cytoplasmic domain upon ligand binding. We propose that neurotrophins activate p75(NTR) by a mechanism involving rearrangement of disulphide-linked receptor subunits.

Analysis of the fracture morphology of polyamide, polyester, polypropylene, and silk sutures before and after implantation in vivo.

This study has analyzed fracture morphology of four nonabsorbable commercially available sutures before and after implantation in rats. Also, tensile and knot strength retention have been evaluated after 3 and 8 weeks in vivo. Scanning electron and optical light microscopes were used for analysis of fracture morphologies and surface changes of the sutures. A clear effect of in vivo on the tensile and knot strength changes, and the fracture mechanism was seen for braided sutures. The suture size was also important for braided sutures, as fibrous tissue formation plays an important role in terms of the size. The fiber's surface properties were also important for the fracture morphology. A smooth and even surface was not suitable for the fibrous tissue formation as seen in monofilament sutures. Therefore, the polymer type was very important for the monofilament sutures, as it was the most important parameter to determine the fracture morphology and was not affected by the implantation and the implantation time. The size of the suture was also important for the polypropylene in terms of axial splitting before and after implantation. This, however, was not the case for knot strength tests. The knot was undone regardless of the size. Surface characteristics were very important for braided sutures, as they have a rough surface that supports tissue formation on the fracture mechanism, tensile and knot strength. Silk suture has single filaments with no regular diameter and smooth surface. Therefore, silk suture has more tissue formation postimplantation compared to polyester suture.